Decimal Day : 50th anniversary and multi-base

“It is estimated that up to six months will be saved in teaching time by the introduction of decimal money”

British Pathe news video clip – ‘Decimalisation (1970)’

On 15th February 1971 Britain changed forever and day to day life would never be the same again. The monetary system went from mixed-base (‘old money’) to base-ten or decimal (‘new money’). Decimal Day ended a run of over 1000 years of a mixed-base money system.

Deci comes from Latin ‘Decimus’ (tenth), which is closely linked to Decem’ (ten). By switching to a base-ten currency, 100 new pence became equal to 1 pound sterling. Gone were all the other exchanges.

The history of the pound sterling goes back to the Romans. The £ symbol is an ornate version of L, for libra, worth one pound mass of silver. Libra is abbreviated as lb which we still use to measure weights. The shilling (s) came from a type of Roman coin called the solidus and the penny was abbreviated with its Latin name denarius (d).

So the old system was abbreviated as £sd (or Lsd for librum, solidus, denarius) or LSD for those groovy 1960s times. The main exchanges were:

1 pound = 20 shillings
1 shilling = 12 (old) pennies

Other coins in use were:

2 farthings = 1 halfpenny
2 halfpence = 1 penny (1d)
3 pence = 1 thruppence (3d)
6 pence = 1 sixpence (a ‘tanner’) (6d)
12 pence = 1 shilling (a bob) (1s)
2 shillings = 1 florin ( a ‘two bob bit’) (2s)
2 shillings and 6 pence = 1 half crown (2s 6d)
5 shillings = 1 Crown (5s)

Although the preparation had been going on for years the currency transition was tricky. Prices were initially shown both in old and new forms. People had to get used to the new pence and other new coins. There were many benefits proposed by the government for going decimal, from reducing teaching time at schools to the use of fewer accountants for businesses.

Even though our monetary system was decimalised all that time back we use mixed-base every day today. Time.

1000 milliseconds to one second (base-ten)
60 seconds to 1 minute (base-sixty)
60 minutes to 1 hour (base-sixty)
12 hous or 24 hour clock

And these days pupils have to understand binary and hex numbers for use in computing.

50 years ago is not that far back and there are many adults who will remember Decimal Day. If you were one of them, I would love to hear your experience of it all. So do drop a comment here on this blog post.

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